lib/windows-spawn.h

   1 /* Auxiliary functions for the creation of subprocesses.  Native Windows API.
   2    Copyright (C) 2001, 2003-2024 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2003.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _WINDOWS_SPAWN_H
  19 #define _WINDOWS_SPAWN_H
  20
  21 /* This file uses _GL_ATTRIBUTE_MALLOC.  */
  22 #if !_GL_CONFIG_H_INCLUDED
  23  #error "Please include config.h first."
  24 #endif
  25
  26 #include <stdint.h>
  27 #include <stdlib.h>
  28
  29 /* Get declarations of the native Windows API functions.  */
  30 #define WIN32_LEAN_AND_MEAN
  31 #include <windows.h>
  32
  33
  34 /* Prepares an argument vector before calling spawn().
  35
  36    Note that spawn() does not by itself call the command interpreter
  37      (getenv ("COMSPEC") != NULL ? getenv ("COMSPEC") :
  38       ({ OSVERSIONINFO v; v.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
  39          GetVersionEx(&v);
  40          v.dwPlatformId == VER_PLATFORM_WIN32_NT;
  41       }) ? "cmd.exe" : "command.com").
  42    Instead it simply concatenates the arguments, separated by ' ', and calls
  43    CreateProcess().  We must quote the arguments since Windows CreateProcess()
  44    interprets characters like ' ', '\t', '\\', '"' (but not '<' and '>') in a
  45    special way:
  46    - Space and tab are interpreted as delimiters. They are not treated as
  47      delimiters if they are surrounded by double quotes: "...".
  48    - Unescaped double quotes are removed from the input. Their only effect is
  49      that within double quotes, space and tab are treated like normal
  50      characters.
  51    - Backslashes not followed by double quotes are not special.
  52    - But 2*n+1 backslashes followed by a double quote become
  53      n backslashes followed by a double quote (n >= 0):
  54        \" -> "
  55        \\\" -> \"
  56        \\\\\" -> \\"
  57    - '*', '?' characters may get expanded through wildcard expansion in the
  58      callee: By default, in the callee, the initialization code before main()
  59      takes the result of GetCommandLine(), wildcard-expands it, and passes it
  60      to main(). The exceptions to this rule are:
  61        - programs that inspect GetCommandLine() and ignore argv,
  62        - mingw programs that have a global variable 'int _CRT_glob = 0;',
  63        - Cygwin programs, when invoked from a Cygwin program.
  64
  65    prepare_spawn creates and returns a new argument vector, where the arguments
  66    are appropriately quoted and an additional argument "sh.exe" has been added
  67    at the beginning.  The new argument vector is freshly allocated.  The memory
  68    for all its elements is allocated within *MEM_TO_FREE, which is freshly
  69    allocated as well.  In case of memory allocation failure, NULL is returned,
  70    with errno set.
  71  */
  72 extern const char ** prepare_spawn (const char * const *argv,
  73                                     char **mem_to_free);
  74
  75 /* Composes the command to be passed to CreateProcess().
  76    ARGV must contain appropriately quoted arguments, as returned by
  77    prepare_spawn.
  78    Returns a freshly allocated string.  In case of memory allocation failure,
  79    NULL is returned, with errno set.  */
  80 extern char * compose_command (const char * const *argv)
  81   _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC_FREE;
  82
  83 /* Composes the block of memory that contains the environment variables.
  84    ENVP must contain an environment (a NULL-terminated array of string of the
  85    form VARIABLE=VALUE).
  86    Returns a freshly allocated block of memory.  In case of memory allocation
  87    failure, NULL is returned, with errno set.  */
  88 extern char * compose_envblock (const char * const *envp)
  89   _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC_FREE;
  90
  91
  92 /* An inheritable handle with some additional information.  */
  93 struct IHANDLE
  94 {
  95   /* Either INVALID_HANDLE_VALUE or an inheritable handle.  */
  96   HANDLE handle;
  97   /* Only relevant if handle != INVALID_HANDLE_VALUE.
  98      It is a bit mask consisting of:
  99        - 32 for O_APPEND.
 100        - KEEP_OPEN_IN_CHILD if the handle is scheduled to be preserved in the
 101          child process.
 102        - KEEP_OPEN_IN_PARENT if the handle is shared with (and needs to be kept
 103          open in) the parent process.
 104        - DELAYED_DUP2_OLDFD if there is a delayed dup2 (oldfd, newfd) and
 105          this IHANDLE is at position oldfd.
 106        - DELAYED_DUP2_NEWFD if there is a delayed dup2 (oldfd, newfd) and
 107          this IHANDLE is at position newfd.
 108      Note that DELAYED_DUP2_OLDFD and DELAYED_DUP2_NEWFD cannot be set in the
 109      same IHANDLE.  */
 110   unsigned short flags;
 111   #define KEEP_OPEN_IN_CHILD 0x100
 112   #define KEEP_OPEN_IN_PARENT 0x200
 113   #define DELAYED_DUP2_OLDFD 0x400
 114   #define DELAYED_DUP2_NEWFD 0x800
 115   /* Only relevant if handle != INVALID_HANDLE_VALUE and flags contains
 116      either DELAYED_DUP2_OLDFD or DELAYED_DUP2_NEWFD.
 117      It is the other fd of the delayed dup2 (oldfd, newfd), i.e.
 118        - for DELAYED_DUP2_OLDFD, the newfd,
 119        - for DELAYED_DUP2_NEWFD, the oldfd.  */
 120   int linked_fd;
 121 };
 122
 123 /* This struct keeps track of which handles to potentially pass to a subprocess,
 124    and with which flags.  All of the handles here are inheritable.
 125    Regarding handle inheritance, see
 126    <https://docs.microsoft.com/en-us/windows/win32/sysinfo/handle-inheritance>.
 127    Whether a handle is actually scheduled for being preserved in the child
 128    process is determined by the KEEP_OPEN_IN_CHILD bit in the flags.  */
 129 struct inheritable_handles
 130 {
 131   /* The number of occupied entries in the two arrays below.
 132      3 <= count <= allocated.  */
 133   size_t count;
 134   /* The number of allocated entries in the two arrays below.  */
 135   size_t allocated;
 136   /* ih[0..count-1] are the occupied entries.  */
 137   struct IHANDLE *ih;
 138 };
 139
 140 /* Initializes a set of inheritable handles, filling in all or part of the
 141    file descriptors of the current process.
 142    If DUPLICATE is true, the handles stored are those of all file descriptors,
 143    and we use DuplicateHandle to make sure that they are all inheritable.
 144    If DUPLICATE is false, the handles stored are only the inheritables ones;
 145    this is a shortcut for spawnpvech().
 146    Returns 0 upon success.  In case of failure, -1 is returned, with errno set.
 147  */
 148 extern int init_inheritable_handles (struct inheritable_handles *inh_handles,
 149                                      bool duplicate);
 150
 151 /* Fills a set of inheritable handles into a STARTUPINFO for CreateProcess().
 152    Returns 0 upon success.  In case of failure, -1 is returned, with errno set.
 153  */
 154 extern int compose_handles_block (const struct inheritable_handles *inh_handles,
 155                                   STARTUPINFOA *sinfo);
 156
 157 /* Frees the memory held by a set of inheritable handles.  */
 158 extern void free_inheritable_handles (struct inheritable_handles *inh_handles);
 159
 160
 161 /* Converts a CreateProcess() error code (retrieved through GetLastError()) to
 162    an errno value.  */
 163 extern int convert_CreateProcess_error (DWORD error);
 164
 165
 166 /* Creates a subprocess.
 167    MODE is either P_WAIT or P_NOWAIT.
 168    PROGNAME is the program to invoke.
 169    ARGV is the NULL-terminated array of arguments, ARGV[0] being PROGNAME by
 170    convention.
 171    ENVP is the NULL-terminated set of environment variable assignments, or NULL
 172    to inherit the initial environ variable assignments from the caller and
 173    ignore all calls to putenv(), setenv(), unsetenv() done in the caller.
 174    CURRDIR is the directory in which to start the program, or NULL to inherit
 175    the working directory from the caller.
 176    STDIN_HANDLE, STDOUT_HANDLE, STDERR_HANDLE are the handles to use for the
 177    first three file descriptors in the callee process.
 178    Returns
 179      - 0 for success (if MODE is P_WAIT), or
 180      - a handle that be passed to _cwait (on Windows) or waitpid (on OS/2), or
 181      - -1 upon error, with errno set.
 182  */
 183 extern intptr_t spawnpvech (int mode,
 184                             const char *progname, const char * const *argv,
 185                             const char * const *envp,
 186                             const char *currdir,
 187                             HANDLE stdin_handle, HANDLE stdout_handle,
 188                             HANDLE stderr_handle);
 189
 190 #endif /* _WINDOWS_SPAWN_H */